Partially selenized FeCo layered double hydroxide as bifunctional electrocatalyst for efficient and stable alkaline (sea)water splitting

Seawater electrolysis to produce hydrogen is a clean and sustainable strategy for the development of clean and sustainable energy storage systems. However, the erosion and destruction of electrocatalysts of the devices by Cl- in seawater during splitting process make it very difficult to realize. In this work, a partially selenized FeCo layered double hydroxide (Se-FeCo-LDH) catalyst is successfully synthesized, which shows good electrocatalytic performance in seawater during water splitting due to both its excellent conductivity and large surface area. Moreover, an anion aggregation layer around the electrode during the catalytic process can be formed to avoid electrode erosion and destruction by Cl- as well as the competitive reaction of chloride oxidation with the oxygen evolution reaction (OER), which not only improves the catalytic efficiency but also the durability of the catalyst. As a result, the overpotential is only 229 mV at a current density of 100 mA cm-2 for OER in 1 M KOH. Only 1.446 V and 1.491 V voltages are required to reach a current density of 10 mA cm-2 in overall alkaline water and seawater splitting, respectively. Besides, this Se-FeCo-LDH catalyst also achieves long-term stability up

Automated summary

Seawater electrolysis for hydrogen production is hindered by the erosion and destruction of electrocatalysts by Cl- in seawater. This study successfully synthesized a partially selenized FeCo layered double hydroxide (Se-FeCo-LDH) catalyst with excellent conductivity and large surface area, which showed good electrocatalytic performance in seawater. Additionally, the formation of an anion aggregation layer around the electrode during the catalytic process prevented electrode erosion and destruction by Cl- and improved catalytic efficiency and durability. These findings lead to low overpotentials and voltages required for efficient water splitting in alkaline water and seawater.